When a figure on AboutAverage is marked provisional, it means the organisation that published it expects it may change. That can look worrying, but it is a sign of honesty, not of a problem.

Fast or final: pick one

Statistics take time to complete. Some records arrive late, some survey answers need checking, and some figures depend on others that aren't finished yet. Statistics offices have a choice: wait until everything is in, or publish a good early estimate now and update it later.

Many choose to publish early and label the figure clearly. Eurostat, for example, flags values as provisional, and national offices publish revision schedules saying when figures will be updated. People who need timely numbers get them, and everyone can see which ones might move.

Why figures change

  • Late information: records that were missing at the first count arrive.
  • Better population figures: many statistics are rates per person. When a census gives a better count of people, figures for earlier years can be recalculated.
  • Method improvements: occasionally a statistics office changes how something is measured, and revises past figures so the series stays comparable.
  • Corrections: rarely, a genuine error is found and fixed, with a note explaining it.

Most revisions are small. A provisional figure is usually a reliable guide; it just isn't the last word.

What we do

We record whether each figure was published as final or provisional, and we show the label next to provisional figures in games and tables. Each answer also says which year it describes and which release it came from, so if a figure is later revised you can see exactly which version we used.

When a statistics office publishes a new version, we don't silently swap numbers. A new release is checked and approved before it replaces the old one, and the sources page lists the releases currently in use.

A made-up example: a country's life expectancy for last year is first published as 82.3 years (provisional). A year later, with complete death records, it is revised to 82.2. Both were the best figure available at the time; only the second is final.

Estimates are not guesses

Some official figures are survey estimates: they come from asking a large random sample, not from counting everyone. They carry a margin of error, which is a measure of how far the estimate might be from the true value because of who happened to be in the sample. We say when a figure is a survey estimate, and we avoid treating tiny differences between estimates as meaningful. More on that in our guide to league tables.